Ferrite switch N-to-M (N:M) networks provide low loss connectivity from N input ports to M output ports, such as in a satellite application where N receive antenna feeds are multiplexed to connect to M receiver chains, where N is greater than M. This terminology will be used below for simplicity, but the N:M network could also operate in a transmit mode where M transmitter chains are multiplexed to N transmit antennas. Further, N:M networks may also be used in redundancy applications, such as where N:M standby redundant amplifiers are provided for M transmit or M receive chains. The N:M switch network can then be used to switch in one or more of the N−M standby amplifiers in case of a failure in one of the M active amplifiers.
In some applications of receive N:M switch networks, it is only critical that the M outputs can connect to any M of the N inputs; therefore, the mapping or the order in which the connections of the M outputs to the N inputs is made does not matter. This significantly reduces the permutations of connections needed and subsequently reduces the complexity of the N:M switch network required. The complex network that provides for all permutations of M to N mappings can be referred to as non-blocking. The simplified networks that are the topic of this invention can be referred to as blocking or order-constrained.
A 1983 technical report by M. L. Burrows titled, “Design of Microwave Beam-Switching Networks,” describes an order constrained ferrite circulator switch network as the optimal circulator switch network approach for connecting N input ports to M output ports. The order constrained network provides the advantages of low insertion loss and parts count (parts=circulator switch junctions and switching electronics). The limiting factor in the order constrained network is that all N inputs cannot connect to all M outputs, so the network is not considered to be “non-blocking.” N is greater than M for this example. The order constrained network does allow that any M of the N inputs can connect to the M outputs, but only in set mappings between the input and output ports.